Seismic cables and a method for manufacturing such

Abstract

A seismic cable ( 1 ) and a method of manufacturing such a cable. The cable includes a plurality of elongated electrical/optical elements which are arranged to be interconnected with a number of seismic sensor devices arranged at intervals along the cable. A polymeric sheath and a protective outer armoring surround the elements to provide protection against radial stress of said cable. The sensor devices are installed outside of the elements and the armoring.

What is claimed is:  
     
       1. A seismic cable ( 1 ) including a plurality of elongated electrical/optical elements which are arranged to be interconnected with a number of seismic sensor devices arranged at intervals along the cable, and with a polymeric sheath surrounding the elements and a protecting outer armouring surrounding said elements and providing protection against radial stress of said cable, characterized in that the sensor devices are installed outside of the elements and the armouring. 
     
     
       2. A cable according to claim  1 , characterized in that the sensor devices are installed in a housing arranged at intervals along the cable outside the armouring. 
     
     
       3. A cable according to claim  1 , characterized in that the polymeric sheath is replaced at intervals along the cable by sleeves surrounding the elements and having outlets for those elements to be interconnected with the sensor devices installed outside the armouring. 
     
     
       4. A cable according to claim  1 , characterized in that each sleeve consist of two interlockable halves having conical end portions. 
     
     
       5. A cable according to claim  3 , characterized in that the sleeves arranged below the armouring are interconnectable with the corresponding housing arranged above the armouring. 
     
     
       6. A cable according to claim  5 , characterized in that both the sleeve and the corresponding housing are provided with interlockable through-holes for the elements to be interconnected with the corresponding sensor devices in the housing. 
     
     
       7. A cable according to claim  3 , characterized in that each sleeve is provided with external studs for distributing the armouring wires on its outer surface. 
     
     
       8. A method for manufacturing a seismic cable according to claim  1 , characterized in that, after bundling or stranding with one another the elements and surrounding them by a sheath, the method comprises removing said sheath along the cable at intervals propose* for the arrangement of the sensor devices and replacing the removed sheath by sleeves, bringing elements to be connected with the sensor devices out of the sleeves through holes in said sleeves before providing said armouring to said cable, wherein the providing of said armouring around said cable comprises the step of stranding the armouring elements around the polymeric sheath as well as around the sleeves replacing the sheath at intervals. 
     
     
       9. A method according to claim  8 , characterized in that an excess of the elements in the area of the sleeves will be achieved by loops of the bundled elements and/or the lay length of the elements stranded with another. 
     
     
       10. A method according to claim  9 , characterized in that the elements are SZ-stranded with another.